ST. MARY’S CATHEDRAL COLLEGE

YEAR 12 ENGINEERING STUDIES EXAMINATION

SEMESTER 1 2009

Time Allowed : 2 hours

(Plus 5minutes reading time)

Question Topic ScoreSection 1 Multiple Choice /10

Section 2- Q1 Historical/ societal issues /4Q2 Historical/ societal issues /5Q3 Engineering mechanics /7Q4 Engineering mechanics /3Q5 Engineering mechanics /6Q6 Engineering mechanics /2Q7 Engineering materials /6Q8 Engineering materials /6Q9 Engineering materials /7

Total /56

Directions to Candidates:

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Answer all questionsCircle correct multiple choice answer

Section I (10 questions, each worth 1 mark = 10 marks)

Q1) Materials used in Public and Personal Transport, also in Civil Structures, have many considerations that must be considered by designing engineers. Which of the following is not a consideration of design engineers:

A. Mechanical propertiesB. Manufacturing processC. Chemical properties D. All of the above considerations are important to design engineers

Q2) How is energy provided to re-charge the battery in a hybrid motor car?

A. A combustion engine burns petrol, which then charges the car’s battery.B. An electric generator is driven by the rotating car wheels when the car is moving.C. An electric generator is driven by the rotating car wheels when the car is braking.D. The battery needs to be plugged into a power point when the car is parked.

Q3) What is the best advantage of using medium carbon steel for train tracks?

A. It is a soft, easily formed steelB. It is a tough metal.C. It has a high coefficient to friction.D. It has high strength in compression.

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The beam in the sketch below is referred to in Q4) and Q5)

Q4) What are the reaction force magnitudes at A and B, provided by the ground on which they sit?

a) Reaction A = 70 kN Reaction B = 130kNb) Reaction A = 100 kN Reaction B = 100kNc) Reaction A = 80 kN Reaction B = 120kNd) Reaction A = 130 kN Reaction B = 70kN

Q5) Which is the correct shear force diagram for the beam?

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Q6) Civil structures such as the Sydney Harbour Bridge do more than simply provide a road way for transport system between both north and south sides of Sydney harbour. An important international social consideration of the Sydney Harbour Bridge is that:

A. people associate the bridge with Sydney and Australia B. people might consider using the bridge for extreme sports such as base jumping C. people know that it is best for mounting fireworks for New Years EveD. it is safer to drive along than to use the Sydney Harbour tunnel.

Q7) Truss analysis is used to determine the magnitude and direction of forces in members, such as beams, in structures such as bridges. What needs to be calculated before method of joints or sections can be used to perform truss analysis.

A. Reaction forcesB. Tension forcesC. Compression forcesD. Applied forces

Q8) Detection of an internal crack in a metal safety mechanism on a train is best found using:

A. dye penetrantB. ultrasonicsC. tension testD. vickers diamond test

Q9) Beams used as floor joists will bend the least when subjected to a point load that is:

A. closest to the reaction forces supporting the beam B. furthest from the reaction forces supporting the beamC. moving sidewaysD. dead!

Q10) What is the power needed to maintain a vehicle at constant velocity of 8m/s if the combined resistance force is 3KN?

A. 2400kWB. 6.66kWC. 24kWD. 666.6kW

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Section II (Worth ….. marks)

Historical and societal influences

Q1) In 1865, architect William Wardell designed St Marys Cathedral for the Catholic church, as a Gothic building. The construction of the spires in 1999 and 2000, so as to complete the original design, was both celebrated and criticised by different parts of Australian society.

a) From a civil perspective, provide an argument why you believe the spires should have been constructed. (1 marks)

………………………………………………………………………………………………..

b) A crane position on the top of the spire was used to lift sandstone blocks into position for the spire, as per the diagram below. If the heaviest block that could be lifted was 100kg, calculate the position of the 250kg counterbalance weight in the crane when lifting that block into position on the spire.

(2 marks) 3000 x

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Counterbalance weight

Steel spire frame

Forming sandstone spire

100kg sandstone block

Crane

Distance x = ………

Distance x = ………...

Q2) Read “Welcome return for a long and winding road” on the stimulus page, then answer the following questions.

a) Why was the original coastal road between Stanwell Park, Coledale, Scarborough and Thirroul closed? (1 mark)

………………………………………………………………………………………………..

b) Describe one impact the new Seacliff Bridge/road has had on business activity in the nearby suburbs. (1 mark)

………………………………………………………………………………………………..

c) The supporting pylons need to be positioned where the reaction force, in the water, is reliable. How could the reaction force of the pylons in the water be ensured with a high ‘factor of safety’, so that the pylon never moves? (1 marks)

………………………………………………………………………………………………..

d) Beams used to support the road between each pylon need to not bend or deform, in any predictable conditions. Sketch and label a simple beam cross-section that has been pre or post stressed to increase its strength in compression, between two pylons used in the Seacliff bridge structure. (2marks)

e) The concrete pylons used for the Seacliff Bridge must also remain rigid or stiff in all weather conditions. How can this property be increased in the concrete pylon. (1mark)

………………………………………………………………………………………………..

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Engineering Mechanics

Q3) A 2 kN force is pulling down on the frame shown below at point D.

a) calculate the reaction force of the wall at point E (2 marks)

Reaction force at point E = …………………..

b) calculate the reaction force of the wall at point C (2 marks)

Reaction force at point C = …………………..

c) calculate the magnitude and direction of the force in member CD (3 marks)

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Magnitude and direction of force in member CD = ……..………..

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Q4) The beam used for member ED has the cross-section shape and size below.

300mm

Ixx = 33 x 10-6 m4

75mm

a) Why is this beam best used in the standing position shown above? (1 marks)

………………………………………………….………………………………………

b) If this beam has a bending moment = 2KNm, calculate the beam’s bending stress. (2 marks)

Shear Force diagram

Beam bending stress = ………………MPa

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Q5) A beam carries four point loads as illustrated below.

(3 marks)

(3 marks)

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Q6) For the truss shown below, calculate the magnitude and nature (either tension or compression) of the force in member CE. (2 marks)

Force in member CE = ……………… kN

Nature of force = ………………………

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Engineering Materials

Q7) Read the article about “Safety ban on heavy trucks” in the stimulus page, then answer the following questions related to material corrosion.

a) Why were trucks that weighed more than 15tonnes stopped from driving over the Cooks River bridge? (1 mark)

…………………………………………………………………………………………

…………………………………………………………………………………………

b) What type of material test was conducted to determine the degrading of the concrete piles supporting the bridge? (1 mark)

…………………………………………………………………………………………

c) The concrete piles had been constructed using a technique of heating the concrete to high temperatures to help them cure, or good hard, in 1962. How has this technique caused weakness in the piles until their repair in 2002. (1 mark)

…………………………………………………………………………………………

d) Describe how this weakening process has been accelerated in the concrete piles.(1 mark)

…………………………………………………………………………………………

e) Draw and label a simple sketch showing a way in which the piles might deform and fail under large compression forces, as applied by heavy vehicles driving over the bridge. (2 marks)

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Q8) Look at the “Pram valet” photo in the stimulus page, then answer the following materials questions.

a) Children prams are useful transport machines used to assist adults when carrying, moving, and protecting infant and young children. Describe three important material considerations the design engineers should make when choosing materials to use for the pram’s frame. (3 marks)

Consideration 1 ………………………………………………………………………

Consideration 2 ………………………………………………………………………

Consideration 3 ………………………………………………………………………

b) A pram is used often by adults when carrying, moving, and protecting infant and young children, hence the pram needs to be tough so that it lasts. Describe one way the pram materials can be made more tough so that they do not break when being used. (1 marks)

…………………………………………………………………………………………

…………………………………………………………………………………………

c) Prams are made using four or three wheels to roll along the ground, as shown in the top view sketches below. From a safety perspective, describe why either the three wheel or four wheel pram can be dangerous for children who like to climb! (1mark)

…………………………………………………………………………………………

d) Considering the size or shape of the pram, how can this problem be overcome? (1mark)

………………………………………………………………………………………….13

Q9) The Sea Cliff Bridge described in question 2, and the Cooks River Bridge in question 7, both need to consider the long term impact of corrosion of all materials used in the bridge structure.

a) What general type of corrosion in most likely to occur on bridge structures? (1 mark)

………………………………………………………………………………………….

b) Describe two different ways the corrosion of metal materials can be minimised in both bridges. (2marks)

………………………………………………………………………………………….

………………………………………………………………………………………….

c) Describe one other way that pylons positioned in or close to the waters edge in both bridges can be damaged over time, apart from collision and corrosion. (1mark)

…………………………………………………………………………………………..

d) Because of changing loads, weather conditions and temperature each day, bridges expand and contract constantly. How can bridges be manufactured or designed so that no crack initially forms and then propagates throughout the bridge structure. (1mark)

…………………………………………………………………………………………..

e) Prams also can be affected by corrosion. Describe how stress corrosion can occur in metal pram parts, also describe how this type of corrosion can be minimised. (2marks)

…………………………………………………………………………………………..

…………………………………………………………………………………………..

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Tuotuo River Bridge, China, Sydney Morning Herald 2006